﻿using Apewer.Models;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;

namespace Apewer
{

    /// <summary>日志记录程序。</summary>
    public sealed class Logger
    {

        private bool _useconsole = true;
        private bool _usefile = false;
        private bool _uselock = false;
        private int _reserved = -1;
        private LogCollector _collector = null;
        private string _lastdate = null;
        private Action<LogItem>[] _actions = new Action<LogItem>[0];
        private List<Action<LogItem>> _actions_list = new List<Action<LogItem>>();
        private object _locker = new object();

        /// <summary>当前日志记录器的名称。</summary>
        public string Name { get; set; }

        /// <summary>已启用。</summary>
        public bool Enabled { get; set; }

        /// <summary>在后台线程处理日志。默认值：FALSE。</summary>
        internal bool Background { get; set; } = false;

        /// <summary>使用控制台输出。默认值：TRUE。</summary>
        public bool UseConsole
        {
            get { return _useconsole; }
            set { if (!_uselock) _useconsole = value; }
        }

        /// <summary>使用日志文件。默认值：FALSE。</summary>
        public bool UseFile
        {
            get { return _usefile; }
            set
            {
                if (_uselock) return;
                if (_cache_count > 0) Flush();
                _usefile = value;
            }
        }

        /// <summary>使用自定义方法。</summary>
        public void UseAction(Action<LogItem> action)
        {
            if (action != null)
            {
                lock (_actions_list)
                {
                    _actions_list.Add(action);
                    _actions = _actions_list.ToArray();
                }
            }
        }

        /// <summary>日志文件的保留天数（不包含今天）。指定 <see cref="FilePathGetter"/> 时此属性无效。</summary>
        /// <remarks>默认值：-1，保留所有日志。</remarks>
        public int FileReserved { get => _reserved; set => _reserved = value; }

        /// <summary>设置过期日志文件的回收程序。指定 <see cref="FilePathGetter"/> 时此属性无效。</summary>
        /// <remarks>默认值：NULL，删除文件。</remarks>
        public LogCollector Collector { get => _collector; set => _collector = value; }

        void Inbackground(Action action)
        {
            if (Background)
            {
                RuntimeUtility.InBackground(() =>
                {
                    lock (_locker)
                    {
                        action.Invoke();
                    }
                }, true);
                return;
            }
            lock (_locker)
            {
                try { action.Invoke(); } catch { }
            }
        }

        internal void Output(string tag, object[] content, Exception exception = null)
        {
            if (!Enabled) return;
            Inbackground(() =>
            {
                var item = new LogItem();
                item.Logger = this;
                item.Tag = tag;
                item.Content = content;
                item.Exception = exception;

                var text = (UseConsole || UseFile) ? item.ToString() : null;
                if (UseConsole)
                {
                    lock (ConsoleLocker)
                    {
                        System.Console.WriteLine(text);
                    }
                }
                if (UseFile)
                {
                    lock (_cache_locker)
                    {
                        if (_cache_capacity > 0)
                        {
                            _cache_array[_cache_count] = text;
                            _cache_count += 1;
                            if (_cache_count == _cache_capacity) Flush();
                        }
                        else
                        {
                            ToFile(text, this);
                        }
                    }
                }

                var actions = _actions;
                foreach (var action in actions)
                {
                    action.Invoke(item);
                }
            });
        }

        /// <summary>创建新实例。</summary>
        public Logger()
        {
            Enabled = true;
        }

        private Logger(string name, bool useConsole, bool useFile, bool enabled)
        {
            Name = name;
            UseConsole = useConsole;
            UseFile = useFile;
            Enabled = enabled;
        }

        #region 文件输出缓存。

        private object _cache_locker = new object();
        private int _cache_capacity = 0;
        private int _cache_count = 0;
        private string[] _cache_array = null;

        /// <summary>设置缓存容量，指定为 0 可取消缓存，较大的日志缓存可能会耗尽内存。</summary>
        public void SetCache(int capacity)
        {
            lock (_cache_locker)
            {
                if (_cache_count > 0) Flush();
                if (capacity == _cache_capacity) return;
                _cache_capacity = capacity > 0 ? capacity : 0;
                _cache_array = (capacity < 1) ? null : new string[capacity];
            }
        }

        /// <summary>将缓存的日志写入文件。</summary>
        public void Flush()
        {
            lock (_cache_locker)
            {
                if (_cache_count < 1) return;
                var sb = new StringBuilder();
                for (var i = 0; i < _cache_count; i++)
                {
                    sb.Append(_cache_array[i]);
                    sb.Append("\r\n");
                }
                ToFile(sb.ToString(), this, false);
                _cache_count = 0;
                _cache_array = new string[_cache_capacity];
            }
        }

        #endregion

        #region 输出。

        internal static object FileLocker = new object();
        internal static object ConsoleLocker = new object();

        /// <summary>获取用于保存日志文件的路径。</summary>
        public static Func<Logger, string> FilePathGetter { get; set; }

        // 向日志文件输出文本，文件名按日期自动生成。
        private static string ToFile(string plain, Logger logger, bool crlf = true)
        {
            lock (FileLocker)
            {
                var path = GetFilePath(logger);
                if (string.IsNullOrEmpty(path)) return "写入日志文件失败：无法获取日志文件路径。";

                var bytes = TextUtility.Bytes(crlf ? TextUtility.Merge(plain, "\r\n") : plain);
                if (!StorageUtility.AppendFile(path, bytes)) return "写入日志文件失败。";
            }
            return null;
        }

        /// <summary>获取日志文件路径发生错误时返回 NULL 值。</summary>
        /// <remarks>默认例：<br/>d:\app\log\1970-01-01.log<br/>d:\www\app_data\log\1970-01-01.log</remarks>
        static string GetFilePath(Logger logger = null)
        {
            var getter = FilePathGetter;
            if (getter != null) try { return getter.Invoke(logger); } catch { }

            // 找到 App_Data 目录。
            var appDir = RuntimeUtility.ApplicationPath;
            var dataDir = Path.Combine(appDir, "app_data");
            if (StorageUtility.DirectoryExists(dataDir)) appDir = dataDir;

            // 检查 Log 目录，不存在时创建，创建失败时返回。
            var logDir = Path.Combine(appDir, "log");
            if (!StorageUtility.AssureDirectory(logDir)) return null;

            // 文件不存在时创建新文件，无法创建时返回。
            var now = DateTime.Now;
            var date = now.Lucid(true, false, false, false);
            var fileName = (logger == null || logger.Name.IsEmpty()) ? $"{date}{FileExt}" : $"{date}_{logger.Name}{FileExt}";

            // 写入文件。
            var filePath = Path.Combine(logDir, fileName);
            if (!StorageUtility.FileExists(filePath))
            {
                StorageUtility.WriteFile(filePath, TextUtility.Bom);
                if (!StorageUtility.FileExists(filePath)) return null;
            }

            // 检查过期文件。
            if (logger != null && getter == null && logger._reserved > -1)
            {
                // 每天执行一次。
                if (date != logger._lastdate)
                {
                    logger._lastdate = date;
                    RuntimeUtility.StartThread(() => CollectFiles(logger, now, logDir));
                }
            }

            // 返回 log 文件路径。
            return filePath;
        }

        static void CollectFiles(Logger logger, DateTime now, string logDir)
        {
            var reserved = logger._reserved;
            if (reserved < 0) return;

            var collector = logger._collector;

            var today = DateTime.Now.Date;
            var paths = StorageUtility.GetSubFiles(logDir);
            foreach (var path in paths)
            {
                // 文件名后缀
                var fileExt = Path.GetExtension(path);
                if (fileExt != FileExt) continue;

                // 文件名格式
                var fileName = Path.GetFileName(path);
                if (fileName[4] != '-') continue;
                if (fileName[7] != '-') continue;
                if (fileName[10] != '.' && fileName[10] != '_') continue;

                // 确定文件名是属于当前的 Logger
                if (logger.Name.IsEmpty())
                {
                    if (fileName.Length != 14) continue; // 2008-08-08.log
                }
                else
                {
                    if (fileName.Length < 16) continue; // 2008-08-08_a.log
                    var loggerName = fileName.Substring(11, fileName.Length - 15);
                    if (loggerName != logger.Name) continue;
                }

                // 从文件名解析日期
                var dt = ClockUtility.Parse(fileName.Substring(0, 10));
                if (dt == null) continue;

                var days = Convert.ToInt32(Convert.ToInt64((today - dt.Value).TotalMilliseconds) / 86400000L);
                if (days > reserved)
                {
                    if (collector == null) StorageUtility.DeleteFile(path);
                    else collector(path, days);
                }
            }
        }

        #endregion

        #region 默认实列。

        private static Logger _default = new Logger(null, true, false, true);
        private static Logger _console = new Logger(null, true, false, true);
        private static Logger _web = new Logger(null, true, false, true);

#if DEBUG
        internal static Logger _internals = new Logger(null, true, false, true);
#else
        internal static Logger _internals = new Logger(null, true, false, false);
#endif

        /// <summary>内部的日志记录程序。</summary>
        public static Logger Internals { get => _internals; }

        /// <summary>默认的日志记录程序。</summary>
        public static Logger Default { get => _default; }

        /// <summary>仅输出到控制台的日志记录程序。</summary>
        public static Logger Console { get => _console; }

        /// <summary>用于 Web 的日志记录程序。</summary>
        public static Logger Web { get => _web; }

        #endregion

        #region 静态。

        const string FileExt = ".log";

        /// <summary>使用 Logger.Default 写入日志，自动添加时间和日期，多个 Content 参数将以“ | ”分隔。</summary>
        public static void Write(params object[] content) => Default.Output(null, content, null);

        /// <summary>使用 Logger.Default 写入日志，自动添加时间和日期，多个 Content 参数将以“ | ”分隔。</summary>
        public static void Write(Exception exception, params object[] content) => Default.Output(null, content, exception);

        /// <summary>压缩日志文件的内容，另存为 ZIP 文件，并删除原日志文件。</summary>
        public static void CollectToZip(string path)
        {
            if (!File.Exists(path)) return;
            var bytes = StorageUtility.ReadFile(path);
            if (bytes.Length > 0)
            {
                var zipDict = new Dictionary<string, byte[]>();
                zipDict.Add(Path.GetFileName(path), bytes);

                var zipData = BytesUtility.ToZip(zipDict);
                if (zipData != null && zipData.Length > 0)
                {
                    var zipPath = path + ".zip";
                    StorageUtility.WriteFile(zipPath, zipData);
                }
            }
            StorageUtility.DeleteFile(path);
        }

        /// <summary>压缩日志文件的内容，另存为 GZIP 文件，并删除原日志文件。</summary>
        public static void CollectToGZip(string path)
        {
            if (!File.Exists(path)) return;
            var bytes = StorageUtility.ReadFile(path);
            if (bytes.Length > 0)
            {
                var gzipData = BytesUtility.ToGzip(bytes);
                if (gzipData != null || gzipData.Length > 0)
                {
                    var gzipPath = path + ".gzip";
                    StorageUtility.WriteFile(gzipPath, gzipData);
                }
            }
            StorageUtility.DeleteFile(path);
        }

        #endregion

        #region public



        #endregion

    }

}
